The present invention involves a device for the injection and mixing of steam into a tank containing a fluid such as water. Through the use of the present invention, one is able to achieve more efficient heat transfer than is otherwise available from competing devices. In addition, the present invention, being of a motionless design, requires less maintenance than competitive steam injection apparatus.
Steam injection has been a unit operation carried out by chemical engineers in processing facilities for as long as chemical engineering has been a science. For example, a typical steam injection water heater was disclosed in U.S. Pat. No. 2,455,498. Subsequently, U.S. Pat. No. 3,984,504 dealt with the fabrication of a rather complex device used to eliminate water hammer which has characterized steam injection systems in the past. It was recognized that such heaters work satisfactorily at relatively low steam pressure such as pressures below 300 psi. At high steam pressures, however, water hammer develops due to the sudden collapse of relatively large steam bubbles which are created by the high pressure steam as it condenses in water.
Steam injection is known as a preferred means of heating water both in a moving stream and in a tank during batch unit operations. There are, however, certain limitations in promoting effective heat transfer between a volume of steam and a fluid contained within a tank. Specifically, steam injection is carried out by introducing a volume of steam within a tank where the steam creates bubbles at relatively high temperature which rise to the surface of a standing fluid only to escape into the surrounding atmosphere. This provides for relatively poor heat transfer and heat distribution. The latter consideration is of principal importance in employing steam to raise the temperature of a large body of fluid where areas within the tank remote from points of steam injection remain at relatively low temperatures. Further, when dealing with an open tank at standard atmospheric pressures, one cannot hope to approach the ideal 212xc2x0 F., the temperature of boiling water. In fact, in most such installations, raising the temperature of the fluid to 140xc2x0 F. is considered a significant achievement. By practicing the present invention, one can achieve uniform temperatures in the vicinity of 190xc2x0 F.
It is thus an object of the present invention to provide a steam injector device which more efficiently distributes thermal energy than devices of the prior art.
It is yet a further object of the present invention to provide a steam injector device without any moving parts in order to reduce operating costs and down time.
These and further objects of the present invention will be more readily appreciated when considering the following disclosure and appended claims.
The present invention is directed to a device for the injection and mixing of steam into a tank containing a fluid. The device comprises a primary steam conduit for receiving steam and for discharging it into a plurality of secondary steam conduits. The primary steam conduit is provided with at least one mixing element positioned therein for inducing an angular velocity to the steam passing through the primary steam conduit. A plurality of secondary steam conduits are provided for receiving steam from the primary steam conduit at their upstream ends and for discharging steam into the tank containing fluid at their downstream ends. Each secondary steam conduit is provided with at least one mixing element proximate its downstream end wherein all such mixing elements induce a rotational angular velocity to the steam exiting said downstream ends.